Solar Photovoltaic Closed Fluid Loop Evaporative Tower

ABSTRACT

A closed fluid loop HVAC system includes an air conditioner or heat pump, an evaporative cooling tower, and fluid input and output lines coupled between the cooling tower and the air conditioner/heat pump. The cooling tower has a solar-powered fluid pump and a solar-powered fan for moving an air stream to cool the fluid in the tower. The closed fluid loop can include a geothermal reservoir with a solar-powered fluid pump for pumping the fluid from the geothermal reservoir.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 61/164,160, filed Mar. 27, 2009, entitled “Solar Photovoltaic Closed Fluid Loop Evaporative Tower,” which is incorporated herein in its entirety by this reference.

BACKGROUND

This invention relates to evaporative towers for building cooling systems. More particularly, it relates to a cooling system evaporative tower that uses photovoltaic solar panels to power a fan and pump combination.

Heating, ventilation, and air conditioning (HVAC) systems consume a large amount of energy. In hot, sunny climates, such as Arizona, HVAC systems consume the greatest amount of energy when cooling the interior of buildings during the daytime. Not only is it expensive to pay for electrical power to operate HVAC systems to provide this cooling, but to meet the peak demand during these times, utilities must make large investments in facilities to generate the required electric power.

It is an object of the present invention, therefore, to provide an improved HVAC system that is more efficient than previously known systems in cooling the interior of buildings.

It is another object of the invention to provide such a system that is suitable for use in residential and commercial cooling systems.

It is yet another object of the invention to provide such a system that conserves energy by utilizing a single renewable energy source, and or a hybrid combination of renewable energy sources.

It is another object of the invention to provide such a system that is relatively inexpensive and easy to install and can be implemented by retrofitting existing HVAC systems.

It is still another object of the invention to provide such a system that helps utilities to reduce peak loads, to balance loads, and to meet their energy conservation goals.

It is yet another object of the invention to provide such a system that can be used with geothermal technology.

Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention.

SUMMARY

To achieve the foregoing objects, and in accordance with the purposes of the invention as embodied and broadly described in this document, there is provided an HVAC system including: thermal transfer means for cooling or heating a temperature-controlled space using a refrigerant; an evaporative cooling tower for cooling a fluid, such as water, and a closed fluid loop including a fluid input line for providing the fluid from the evaporative cooler to the thermal transfer means and a fluid output line for providing the fluid from the thermal transfer means to the evaporative cooler. The evaporative cooling tower includes a fan for moving an air stream to cool the fluid. A solar-powered fluid pump is provided for pumping fluid through the cooling tower. A solar-powered motor is provided for driving the cooling tower fan.

According to one aspect of the invention, the means for cooling or heating the temperature-controlled space can include an air conditioner or a heat pump, such as a fluid-to-air heat pump. The closed fluid loop can include a geothermal reservoir, and a solar-powered fluid pump can be provided for pumping the fluid from the geothermal reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate the presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred methods and embodiments given below, serve to explain the principles of the invention.

FIG. 1 is a schematic diagram of one embodiment of a HVAC system utilizing a solar-powered closed-loop fluid evaporative tower in accordance with the present invention.

FIG. 2 is a schematic diagram of another embodiment of a HVAC system utilizing a solar photovoltaic closed fluid loop evaporative in conjunction with an engineered geothermal reservoir and a fluid-to-air heat pump.

DESCRIPTION

Reference will now be made in more detail to presently preferred methods and embodiments of the invention, as illustrated in the accompanying drawings. While the invention is described more fully with reference to these examples and drawings, the invention in its broader aspects is not limited to the specific details, representative devices, and illustrative examples shown and described. Rather, the description which follows is to be understood as a broad, teaching disclosure directed to persons of ordinary skill in the appropriate arts, and not as limiting upon the invention.

Referring to FIG. 1, there is shown one embodiment of a HVAC system 10 according to the present invention. The HVAC system 10 includes an air handler unit 12 and a condensing unit 14. In unitary package HVAC systems, the air handler unit 12 and the condensing unit 14 are housed in a single location, typically on the roof of the building to be cooled. In other systems, the air handler unit 12 is located inside the building and the condensing unit 14 is located outside of the building.

The air handler unit 12 includes an evaporator coil 16 and a blower 18 for drawing outdoor air flow A and return air flow B (from the space to be cooled) into the air handler unit 12 and forcing cooled air flow C out of the air handler unit 12 and into the space to be cooled. Cooled, liquid refrigerant flows through a refrigerant line 20 controlled by a metering device 22 and through the evaporator coil 16. Air flows A and B flow over the evaporator coil 16 and are thereby cooled before entering the space to be cooled as cooled air flow C. In one embodiment, an optional pre-cooler radiator 24 pre-cools the air flow A as it is drawn into the air handler unit 12, as will be explained in more detail below.

The condensing unit 14 includes a condenser fan 26, a condenser coil 28, a compressor 30 and a sub-cooling heat exchanger 31. The condenser fan 26 draws a flow of outside air AA over the condenser coil 28. The compressor 30 changes the refrigerant into a high temperature, high pressure gas, which flows via gas line 32 through the condenser coil 28. As this refrigerant gas flows through the condenser coil 28, it loses heat and condenses into a high temperature, high pressure liquid. This liquid refrigerant flows through a liquid line 34 into the sub-cooling heat exchanger 31, which cools the refrigerant as described in more detail below. The sub-cooled liquid refrigerant flows through the refrigerant line 20 to the evaporator coil 16, where it changes state into a low temperature, low pressure gas. This refrigerant gas absorbs heat from the air flows A, B over the evaporator coil 16 and becomes super-heated refrigerant, which returns via a return suction line 35 to the compressor 30. By way of example, on a hot day in Phoenix, Ariz., the outside air AA can be 115° F., the high temperature, high pressure refrigerant gas in gas line 32 can be about 170° F., the liquid refrigerant in line 34 can be about 120° F. and the sub-cooled liquid refrigerant in line 20 can be about 80° F.

Still referring to FIG. 1, an evaporative tower 40 with a closed fluid loop provides cooled fluid to the sub-cooling heat exchanger 31 and the pre-cooler radiator 24 via fluid input lines 42. Fluid output lines 44 return the closed loop fluid to the evaporative tower 40. The evaporative tower 40 cools the closed loop fluid by absorbing heat in the fluid through the walls of the closed-loop tubes to the evaporative cooled water on the exterior of the loop tubes. The evaporative tower includes a fan 46 for moving the air stream and a fluid pump 48 for pumping the closed loop fluid through the system. Advantageously, the fan 46 and fluid pump 48 are solar powered. A solar photovoltaic panel 50 converts the solar energy to power the fan 46 and pump 48. In one advantageous embodiment the closed loop fluid is water. Upon reading this disclosure, however, those of skill in the art will recognize that other suitable fluids can be used.

One suitable evaporative tower, which can be converted to utilize solar power as disclosed herein, is marketed by Thermal Flow, of Fort Worth, Tex., at www.thermalflow.net. This evaporative tower can be modified to include a solar-powered fan motor assembly. One such suitable fan motor assembly is that used by Lennox on its SunSource™ solar-assisted heat pump. A suitable solar photovoltaic panel 50 for powering such a fan motor assembly is the Kyocera KD205GX-LP photovoltaic module. A suitable fluid pump 48 for this evaporative tower is a Grundfos BP10727 well water pump, which can be powered by three Kaneka GSA-60 solar modules. A suitable pump control unit is the Grundfos CU 200 SQ Flex pump control unit, which enables connection of a switch that can energize or de-energize the pump and fan on demand.

Referring to FIG. 2, another embodiment of a HVAC system 10 according to the present invention includes the solar photovoltaic closed fluid loop evaporative tower 40 used in conjunction with an engineered geothermal reservoir 52, a heat pump 38 and a solar thermal panel 54 to achieve energy efficiency and capacity gains in controlling the temperature of a temperature-regulated space, such as a living space in a home.

In the embodiment of FIG. 2, the heat pump 36 is a fluid-to-air heat pump as is known in the art, which operates on the basic principle of heat transfer. The heat pump uses a relatively small amount of energy to transfer heat from a heat source into a heat sink. The heat pump 36 typically includes fans, (not shown) refrigerator coils (not shown), a compressor (not shown), and a reversing valve (not shown). The reversing valve reverses the flow of the refrigerant, so that the system can operate in one of two modes—i.e., transferring heat into or out of the temperature-regulated space. Referring to FIG. 2, the heat pump 36 provides the air flow C into the temperature-regulated space, which air flow can be a cooled air flow or a heated air flow depending on the mode of operation of the heat pump 36.

Referring to FIG. 2, the closed fluid loop has a fluid input line 42 that provides cooled fluid to the heat pump 36 from the evaporative tower 40, as previously described. Also similar to the system previously described, the closed fluid loop has a fluid output line 44 that returns hot closed loop fluid to the evaporative tower 40, which cools the closed loop fluid as previously described. In the embodiment of FIG. 2, the closed fluid loop also includes an engineered geothermal reservoir 52 in the output line 44 between the heat pump 36 and the cooling tower 40. The geothermal reservoir 52 provides a relatively large thermal mass or heat capacity, which can be used in conjunction with the heat pump 36 to regulate the temperature of a space, such as the space in a home, e.g., by cooling the space in the warm weather and heating the space in cool weather. In one preferred embodiment the geothermal reservoir 52 includes a body of water, such as swimming pool or other reservoir in the ground for holding water. One particularly advantageous geothermal reservoir is a vertical column reservoir drilled into the ground and lined for holding water.

Still referring to FIG. 2, in a typical cooling operation during a hot day, cooled closed loop fluid (e.g., water at 75° F.) is provided to the heat pump 36 by fluid input line 42 b. The heat pump 36 transfers heat from the space to be cooled into the closed loop fluid, thereby cooling the space and heating the closed loop fluid. The heated closed loop fluid exits the heat pump 36 at an increased temperature (e.g., about 81° F. for water) via output line section 44 a and is returned to the geothermal reservoir 52 via output line sections 44 b, 44 c. A thermostatically actuated a control valve 58 directs the closed loop fluid to line section 44 b so that it bypasses the solar thermal panel 54, which is discussed in more detail below. The geothermal reservoir 52 cools the closed loop fluid as heat is transferred from the fluid in the geothermal reservoir 52 to the surrounding ground. A reservoir pump 62 pumps the relatively cool reservoir fluid out of the geothermal reservoir 52 through output line section 44 d. In one advantageous embodiment, one or more solar photovoltaic panels 50 can be used to convert the solar energy to power the reservoir pump 62. In the embodiment of FIG. 2, the closed loop fluid is water. As previously discussed, however, those of skill in the art will recognize that other suitable fluids can be used.

If additional cooling of the closed loop fluid is required, the fluid is directed to the cooling tower 40 via output line segment 44 e. This is achieved by a control valve 47, which is thermostatically controlled. If the closed loop fluid in output line section 44 d is greater than a specified temperature (e.g., about 75° F. for water), the control valve 47 can be thermostatically actuated to direct the closed loop fluid to the cooling tower 40. The cooling tower 40 operates as previously described to further cool the closed loop fluid (e.g., to about 75° F. for water), which is then pumped via fluid input lines 42 a, 42 b to the heat pump 36. On the other hand, if the closed loop fluid in output line section 44 d is less than the specified temperature such that further cooling by the cooling tower is not needed, the control valve 47 can be thermostatically actuated so that the closed loop fluid is directed through cooling tower bypass line 45, thereby bypassing the cooling tower 40.

Still referring to FIG. 2, in a typical heating operation during a cold day, the temperature of the ground—and the closed loop fluid in the geothermal reservoir 52 and in output line section 44 d—will be greater than the outside air temperature. The control valve 47 will be thermostatically actuated so that the closed loop fluid is pumped through the cooling tower bypass line 45, thereby bypassing the cooling tower 40. The heat pump 36 is operated to transfer heat from the closed loop fluid into the inside space to be heated, thereby cooling the closed loop fluid. The cooled closed loop fluid exits the heat pump 36 at a decreased temperature via the output line section 44 a and is returned to the geothermal reservoir 52 via output line sections 44 b, 44 c. The geothermal reservoir 52 warms the closed loop fluid as heat is transferred from geothermal reservoir 52 and the surrounding ground into the closed loop fluid. The reservoir pump 62 pumps the relatively warm reservoir fluid out of the geothermal reservoir 52 through output line section 44 d.

If additional heating of the closed loop fluid is required, the control valve 58 directs the fluid to the solar thermal panel 54 via a solar thermal panel line 56. If additional heating is not required, the control valve 58 can be thermostatically actuated to direct the closed loop fluid through the line segment 44 b, thereby bypassing the solar thermal panel 54. In one preferred embodiment, the solar thermal panel 54 is of the type typically used on residences to provide domestic hot water. If the geothermal reservoir 52 includes a swimming pool, in addition to heating an interior space, the configuration of FIG. 2 can be used to heat the swimming pool on cold days.

Having read this disclosure, it will also be understood by those having skill in the art that modifications may be made to the invention without departing from its spirit and scope. For example, the solar photovoltaic closed fluid loop evaporative tower can be combined with the liquid line sub-cooling heat exchanger, and a geothermal reservoir in order to modify an existing heating, ventilation, air conditioning and refrigeration (HVACR) system.

Therefore, the invention in its broader aspects is not limited to the specific details, representative devices, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept. 

1. An HVAC system comprising: thermal transfer means for cooling or heating a temperature-controlled space using a refrigerant; an evaporative cooling tower for cooling a fluid in a closed fluid loop, wherein the evaporative cooling tower includes a fan for moving an air stream to cool the fluid; a solar-powered fluid pump for pumping the closed loop fluid through the cooling tower; and a solar-powered motor for driving the cooling tower fan; wherein the closed fluid loop includes a fluid input line for providing fluid from the evaporative cooler to the thermal transfer means and a fluid output line for providing fluid from the thermal transfer means to the evaporative cooler;
 2. The HVAC system of claim 1 wherein the means for wherein the means for cooling or heating the temperature-controlled space comprises an air conditioner.
 3. The HVAC system of claim 1 wherein the means for cooling or heating a temperature-controlled space comprises a heat pump.
 4. The HVAC system of claim 3 wherein the heat pump is a fluid-to-air heat pump.
 5. The HVAC system of claim 1 wherein the fluid includes water.
 6. The HVAC system of claim 1 wherein the closed fluid loop includes a geothermal reservoir.
 7. The HVAC system of claim 6 further including a solar-powered fluid pump for pumping fluid from the geothermal reservoir. 